Signaling system



April 12, 1927.

1. 1,624,395 A. M. CURTIS S IGNALING SYSTEM Filed Aug. 22. 1924 lllllll L L m 50 38 /nven/or:' Aw/Pn M 0/17.;

Patented Apr. 12, 1927.

UNITED STATES PATENT OFFICE,

AUSTEN M. CURTIS, OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

SIGNALING- SYSTEM,

This invention relates to signaling systems, more particularly to those for use on long submarine cables, and it has for its object a signaling system in which the signaling impulses receivedover the line are amplified in such a manner as to permit the use of a plurality of receiving circuits which are in no way affected by each other.

In various types of signaling systems, it 1 is essential to maintain synchronism between the sending and receiving apparatus installed at the opposite ends of the line. In the case of ordinary telegraph systems, this is easily accomplished, but where the received signals are weak, as is the case when signaling over long submarine cables, it is necessary to provide an amplifier for strengthening the received signals, which are distorted by the cable in a manner which makes it more diflicult to obtain the desired de ree of synchronism.

n the usual method of maintaining syn,

chronism, there is employed a polar relay which oscillates from one contact to the other as the line current reverses. This relay is.

connected with 'a brush on the receiving distributor in such a manner that the speed of the distributor is corrected in accordance with the position of the brush at the instant the line relay reverses its position. In order 40 of the received signal among a plurality of low speed receiving mechanisms, such, for example, as printers or siphon recorders, and

- in order to minimize the effects of line interference, it is usual to select only a portion of the received signal wave, rejecting the remainder. Consequently, in such a system there must be two circuits, one, for synchronizing purposes, containing a relay operated by the entire shaped signal current,

and the other containing the receiving mechanism which is operated by only a portion of the signal current. This modification of the wave form of the signal current is accomplished by intermittently connecting and disconnecting the receiving relay or recorder from the output circuit of the receiving ampllfier by means of a synchronously operated distributor. Evidently, the receiving relay and the line relay cannot be connectedin series since the line relay would then recelve only a portion of the signaling current and would be unsuitable for synchronizing purposes. Again, if the line relay and recelvlng relay are connected in parallel, the distributor being in series with the receiv-- mg relay only, the signal in the line relay W111 be distorted, first, by the fact that when the receiving relay is connected to the ainplifier output circuit by"means of the distrlbutor, the amplifier output voltage will be reduced; and second, because when the rece1v1ng relay armature is operated it induces in the relay winding a current impulse which will produce an additional volta e across the terminals of the line relay. n either case, the distortion of therecelved signal is sufficient to make the operation of the synchronizing line relay uncertain and thereby produce errors in synchronization. In case it is desired to use a vibrating relay in the receiving circuit, the simultaneous operation of the synchronizing and receiving relays is further complicated resulting in in-.-

creasing the synchronizing errors. Signaling currents such, for example, as those employed in submarine signaling systems involve a-plurality of frequencies depending upon the speed of sending and also upon the characters transmitted. In-order to obtain satisfactory shaping of the received signal impulses, it is desirable that there be no suppression of frequencies up to those at least 50% higher than the fundamental sending frequency. As the result of recent improvements in submarine signaling it is now possible to transmit atzspeeds appreaching 100 cycles and the frequencies involved in such systems therefore varyfrom about zero up to 150 or 200 cycles. In accordance with the features of this invention a plurality of amplifying devices are provided for amplifying received signaling impulses involving these frequencies, all of such devices being responsive to the same frequencies but cooperating with other means for performing independent operations without in' any way reacting upon each other.

In accordance with another feature of the present invention, the amplifier for increasing the strength of the received signal is provided with a plurality of output stages having their grids in parallel but their plates connected in separate circuits. One of these plate circuits may be used for synchronizing purposes since it contains the complete received impulse, and the other plate circuits may be employed in various ways without affecting the operation of the circuit employed for synchronizing purposes. These and other features of the invention will be more clearly understood by reference to the accompanying drawing showing one embodiment of the invention.

Referring to the drawing, an amplifier A, located at the receiving end of a long submarine cable, is provided with two output sta es, one used for synchronizing purposes an the other for receiving. The filament andgrid elements of amplifiertube 5 are connected in multiple with the filament and grid elements of amplifier tube 6, but the plate circuits are separate. The plate circuit for amplifier tube 5 comprises a variable resistance 7, battery 8 and variable resistance 9. By varying the point of connection to battery 8 and regulating the value of resistance 9,it is possible to compensate for the normal space current flowing through the amplifier tube without in any way distorting the wave form of the current impulse. The filament of amplifier tube 5 is connected to common ring 10 of the receiving section of a rotating distributorand by means of brush 11 is connected successively with segments 12, 13, 1 1, 15 and 16. These segments are connected respectively to receiving instruments 17, 18, 19, and 21, the other terminals of which are connected in common and to the movable battery tap 22. The receiving instruments 17, 18, 19, 20 and 21 may be direct writers, siphon recorders or the magnets of a five unit printing system.

The plate circuit of amplifier tube 6 includes the variable resistance 25, fixed resistance 26 and battery 2". In parallel with the resistance 26 is connected a polar relay 28 in series with a condenser 29. The variable resistances 7 and are provided for the pur pose of overcoming any tube distortion and the condenser 29 1s rovided for the purpose of keeping the dlrcct current from bat tery 27 out of the windings of relay 28. The armature of relay 23 in the position shown engages contact 30 which is connected through condenser 31 and resistance 32 in parallel to a common ring 33 on the correcting face of the distributor. When operated in the reverse direction, the armature of relay 28 engages contact 34 which is connected to common ring 33 in a similar man ner through condenser 35 and resistance 36. This armature is permanently connected to i one terminal of battery 37,. the other terminal of which is connected to the mid-point of the windings of the correcting relay. The other terminal of winding 38 is connected to alternate segments 3 on the correcting face of the distributor, while the other terminal of winding 39 is connected to the alternate segments 7 on thecorrecting face of the distributor. This distributor is driven by means of a La Tour motor M which is, in turn, driven by the tuning fork I.

This motor is ofthe Well known phonic wheel type and consists of a rotor 40, a pair of operating magnets all and 42 having their windings connected in parallel and a second pair of operating magnets 43 and a l also having their windings connected in parallel. The magnets 4:1 and 42 are connected to an outer contact member 15 of tuning fork F, and the operating magnets 43 and 14 are connected to an inner contact member 46 of tuning fork F. This fork is maintained in operation by means of a magnet 50, one terminal of which is connected to contact 51 and the other terminal is connected to the armature of the correcting relay. A grounded source of energy 55 is connected to the tines of fork F and, in conjunction with operating magnet 50, maintains the fork in vibration. A resistance 56 is inserted in the operating circuit of the fork but is shortcircuited when armature 53 engages contact 57.

In the operation of the system, a received signaling impulse, as it passes through amplifier A at the last stage, affects equally the amplifier tubes 5 and 6. The signaling current received at the amplifier tube 5 passes through a compensating circuit consisting of battery 8 and resistance 9, and is then connected in order to the receiving mechanisms 17 to 21 by means of the brush 11 successively engaging segments 12 to 1G and connecting them with segment 10. These receiving mechanisms may consist, of any of, the well known types of receivers, such as siphon recorders, direct writers, or the op erating magnets of a printing mechanism. In accordance with the well-known practice, only a portion of the received signal wave will be impressed upon the receiving mechanism, but, for the sake of clearness, no

means is shown for breaking up the current wave.

The amplifier tube 6 will beinfluenced in a similar manner by the signaling impulse and will cause the operation of relay 28., At

each reversal of the signaling current, the

armature of relay 28 reverses and thus allernatel y engages contacts 30 and 3+t. Let it be assumed that the armature is moved from 1 the position shown and into engagement with contact 3 1, in which case a charging current flows from battery 37 through the armature and contact 34: of relay 28, condenser 35, common segment 33 and then through brush 58 and either a slow segment the instant the armature of 'relay 28 engages contact 34, the brush 58 is resting on a slow segment, the circuit is closed through winding 38 of the correcting relay, and, since the preceding operation of. this relay was in a slmilar dlrection, no change in operation will now take place. However, if, at the particular instant, the armature of relay 28 engages contact 34, brush 58 is wiping over a fast segment f, winding 39 is energized,

causing the operation of armature53 to engage contact 57 and thus place a short circuit across resistance 56. Since resistance 56 is in the operating circuit ofthe forkmagnet 50, this operation causes a larger current to flow through the operating "winding of the fork which may be traced from grounded battery 55 through thelower tine of fork F, contact 51, operating magnet and contact 57, to ground. As aresult of this high operating: current, the amplitude of vibration of the fork tine is increased and its frequency isthereby slightly decreased.

In its outward swing, the upper fork tine engages contact 45, thereby completing an operating circuit for motor M from the grounded source of energy through contact 45 tomagnets 41 and 42 of the motor.

As the forktine swings in the reverse di rectionit engages contact 46 and the operating circuit for the motor is completed from the source of energy 55 through contact 46 and to operatin magnets 43 and 44. The speed of motor fi l is thus controlled by the speedof vibrations of fork F. Under the conditions mentioned above, when brush 58 connects one of the fast segments f with ring 33 and theresistance 56 is shorted, in consequence, the frequency of fork F is decreased slightly, thus decreasing the speed at which the distributor is driven until the point is reached where the brush 58 engages one of the slow segmentss at the time of the reversal of'the signal current. -When this occurs, an operating pulse is caused to flow through the winding 5380f the correcting relay, thus opening the short circuit across resistance'56 and causing the fork F to again increase ightlylin frequencyhe pnrpiose of inco'ming signaling currents, said ampli-- of resistances 32 and 36 is toallowthe charge on condensers 3l'and 35 to leak off between successive operations of the relay.

At the frequencies eifiployed in cable telegraphy, the reaction between-:the plate and grid circuits of vacuum tubes 5 and 6 is negligible. Accordingly, the plate circuit of tube 5 may be employed for operating various types of receiving mechanisms and the wave orm may be curbed or otherwise altered without causing any reaction which distorts the current waves in the output ci rcuit of tube 6. Thus, this latter output circuit may be used for obtaining accurate synchronism in the manner described or itmay i be employed for other purposesiwhere an undistorted signaling circuit is desirable.

What is claimed. is:

1.,'-A signaling system including a plurality of amplifying devices for amplifying received signal impulses involving waves of a plurality of frequencies, and means individual to each of said devices and responsive to waves of frequencies, which are in part, at least, identical, for performing different operations.

2. A signaling system including a plurality of space discharge repeating devices for repeating received si al impulses involving waves of a pluraht of frequencies and independent means in ividual to each of said devices and responsive to waves of frequencies, which are in part, at least, identical, ,for performing different operations. v

3: In a signaling system, an amplifier for increasing the strength of received impulses involving wavesv of a plurality of frequencies, a plurality of'output circuits for said amplifier, and means individual to each of said output circuits and responsive to Waves of frequencies, which are in part, at least, identical, for performing different operations.

4. In a signaling system, an electron discharge amplifier including a pair of vacuum tubes having their grid circuits in parallel and their plate circuits separate, and means individual to each of said plate circuits for performing different operations, each of said means being responsive to waves of frequencies, which are inpart, at least;

fier comprising a plurality of output cir,- cuits, a plurality of receiving mechanisms individual to one of said output circuits, a distributor for successively associating said receiving mechanisms with said output circuit, and means included in another of said 'outputcircuits and responsive to the reversal of the signaling current for maintaining said distributor in synchronism with the received signals.

In witness whereof, I hereunto subscribe my name this 16th day of August A. D.,

AUSTEN M.v CURTIS. 

